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8958 



Bureau of Mines Information Circular/1983 




Cost Estimate of the Bayer Process 
for Producing Alumina— Based 
on 1982 Equipment Prices 

By Deborah A. Kramer and Frank A. Peters 



-> 




UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 8958 

u 



Cost Estimate of the Bayer Process 
for Producing Alumina— Based 
on 1982 Equipment Prices 

By Deborah A. Kramer and Frank A. Peters 




UNITED STATES DEPARTMENT OF THE INTERIOR 
James G. Watt, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 




* 



1 v* / 



Library of Congress Cataloging in Publication Data: 



Kramer, Deborah A 

Cost estimate of the Bayer process for producing alumina, based 
on 1982 equipment prices. 

(Bureau of Mines information circular ; 8958) 

Bibliography: p. 9. 

Supt. of Docs, no.: I 28.27:8958. 

1. Aluminum industry— United States— Costs. 2. Aluminum— Metal- 
lurgy— Economic aspects— United States. 3. Aluminum ores — Economic 
aspects-United States. I. Peters, Frank A., 1931- . II. Title. III. 
Series: Information circular (United States. Bureau of Mines) ; 8958. 

TN295,U4 [HD9539.A63U491 622s [669'. 722] 83-600317 



5 



CONTENTS 



Page 



Abstract 1 

Introduction 2 

Process description 2 

Bauxite handling and slurry preparation section 3 

Digestion section 3 

Clarification section 4 

Precipitation and decomposition section 4 

Caustic regeneration section 5 

Economics 5 

Capital costs 5 

Operating costs 7 

References 9 

Appendix. — Utility requirements, equipment cost summaries, and material 

balances 10 

ILLUSTRATIONS 

1 . Bayer process flowsheet 3 

A-l. Material balance, bauxite handling and slurry preparation section 18 

A-2. Material balance, digestion section 18 

A-3 . Material balance , clarification section 19 

A-4. Material balance, precipitation and decomposition section 19 

A-5. Material balance, caustic regeneration section 20 

TABLES 

1 . Composition of hypothetical bauxite (dry basis) 3 

2. Estimated capital cost 6 

3. Estimated annual operating cost 8 

A-l . Raw material and utility requirements 10 

A-2. Direct labor requirements, operators per shift 10 

A-3 . Maj or items of equipment 10 

A-4. Equipment cost summary, bauxite handling and slurry preparation section.. 11 

A-5. Equipment cost summary, digestion section 13 

A-6. Equipment cost summary, clarification section 14 

A-7. Equipment cost summary, precipitation and decomposition section 15 

A-8. Equipment cost summary, caustic regeneration section 16 





UNIT OF MEASURE 


ABBREVIATIONS USED IN 


THIS REPORT 


Btu/d 


British thermal unit 


kW'h 


kilowatt -hour 




per day 




Mgal 


thousand gallons 


°C 


degree Celsius 




min 


minute 


d/wk 


day per week 




pet 


percent 


d/yr 


day per year 




psia 


pound per square inch, 


°F 


degree Fahrenheit 




- 


absolute 


ft 


foot 




ton/d 


short ton per day 


ft 2 


square foot 




ton/h 


short ton per hour 


gal 


gallon 




ton/yr 


short ton per year 


h 


hour 




wt pet 


weight percent 


h/d 


hour per day 




yr 


year 


in 


inch 









COST ESTIMATE OF THE BAYER PROCESS FOR PRODUCING 
ALUMINA-BASED ON 1982 EQUIPMENT PRICES 

By Deborah A. Kramer and Frank A. Peters 



ABSTRACT 

This Bureau of Mines report presents a cost estimate of the Bayer 
process, which is used for virtually all cell-grade alumina production. 
The report will serve as a reference point to determine the economic 
merits of processes that have evolved from Bureau of Mines investiga- 
tions on technology for producing alumina from domestic nonbauxitic raw 
materials. 

The Bayer process involves dissolving the alumina present in bauxite 
in a caustic solution at high temperature and pressure. After the un- 
dissolved impurities are removed, the solution is seeded to produce an 
alumina trihydrate precipitate. This precipitate is filtered, washed, 
and calcined to produce the cell-grade alumina product. 

This cost estimate is for a plant producing 1 million tons of alumina 
per year. The estimated operating cost is approximately $250 per ton 
of alumina. 



^ Chemist, Avondale Research Center, Bureau of Mines, Avondale, MD. 

2 Chief, Process Evaluation, Avondale Research Center, Bureau of Mines, Avondale, MD, 



INTRODUCTION 



Since the United States has very lim- 
ited high-grade bauxite deposits, it is 
dependent on imported bauxite to supply 
virtually all its alumina needs-. To pro- 
vide technology that may help reduce this 
country's dependence on imported bauxite, 
the Bureau of Mines has conducted re- 
search on methods for recovering alumina 
from domestic raw materials such as clay, 
anorthosite, alunite, dawsonite, and coal 
shale and ash. 

To determine the relative economic 
attractiveness of the technology being 
considered, a reference point is needed. 
A cost estimate of the Bayer process was 
prepared to provide the reference point, 
since this method is used for virtually 
all commercial alumina production. The 
same estimating techniques are used in 
this cost estimate as are being used in 
the economic studies of proposed pro- 
cesses for producing alumina from non- 
bauxitic raw materials in order to pro- 
vide greater confidence in comparing 
various technologies. 



This cost estimate is based on a previ- 
ous one prepared by the Bureau of Mines 
(_1_) , 3 incorporating additional technical 
information to update the technology. 
This information includes data on current 
Bayer practice such as a higher digestion 
temperature and pressure, an increased 
number of flash stages , impurity removal 
through bleed stream treatment, and solu- 
tion composition. Equipment design and 
costing methods reflect current evalua- 
tion techniques. 

The Bayer process was patented in 1894 
by Karl Josef Bayer GO . Although modi- 
fications have been made, the process is 
basically the original one. Most modifi- 
cations have centered on leaching and 
solid-liquid separation conditions that 
have been required to adapt the process 
to different bauxite feeds. Jamaican 
bauxite is used as the feed for the pro- 
posed plant in this study. 



PROCESS DESCRIPTION 



Bauxite is mixed with a caustic leach 
solution and then pumped to digestion 
vessels where the temperature and pres- 
sure are increased in order to dissolve 
the alumina. Undissolved impurities are 
removed from the solution, and alumina 
trihydrate is precipitated by seeding the 
solution with fine trihydrate crystals. 
The trihydrate crystals are separated 
from the solution and calcined to produce 
the final alumina product. A basic pro- 
cess flowsheet is shown in figure 1. 



equipment , which allows for downtime for 
maintenance without reducing plant capac- 
ity. For convenience, the plant has been 
divided into five major sections. The 
material balance for each section is pre- 
sented in the appendix. Jamaican baux- 
ite, a mixture of alumina monohydrate and 
trihydrate, is used as a feed for the 
proposed plant. An analysis on a dry 
basis is given in table 1. The bauxite 
also contains moisture equal to 15 pet of 
the dry components. 



New Bayer plants are being built with 
capacities exceeding 800,000 ton/yr. 
Large plants can be built without techni- 
cal risk because of the maturity of the 
Bayer technology. Therefore, the pro- 
posed plant has been designed to produce 
1 million tons of alumina per year and to 
operate 3 shifts per day, 365 d/yr at a 
gulf coast location. For economic rea- 
sons, Bayer plants are designed for 
continuous operation by adding spare 



The bauxite handling and crushing fa- 
cilities consist of one line of equip- 
ment ; however , the remainder of the plant 
is designed with three operating lines 
and spare equipment to insure continuous 
production when maintenance is required. 



3 Under lined numbers in parentheses re- 
fer to items in the list of references 
preceding the appendix. 



Bau) 

1 


ite 

1 


Lime 

1 






Steam 

1 




quor 

Recovered steam 






PUG MIXING 




DIGESTION 








J 


I 




II 


Digestion li 

1 










1 








FLASH COOLING 














" 










Flocculant * 


THICKENING 




FILTRATION 


Filter cake ,. . 

wash watpr 




















1 








" 1 




Filtrate and washings 








' 








• liquor 




V 






V 








Wash 

water 


WASHING 




PRECIPITATION 




THICKENING 




FILTRATION 
AND WASHING 








< 


* 
















n 


' 




















1 
Red 


mud 




Seed c 


rystals 


Spent liquor 


A1 2 3 -3H 2 














v 




, , Ti Iter cake 










EVAPORATION 




CALCINATION 










Makeup 






Water 














caustic 




vapor 


Stack gases 






-n 


























Alumina 









Recycle caustic 

FIGURE 1. - Bayer process flowsheet. 



For convenience, only one line of equip- 
ment is described in the plant 
description. 

TABLE 1. - Composition of hypothetical 
bauxite (dry basis) 1 



Component 



wt pet 



A1 2 3 49.0 

Fe 2 3 20.0 

Si0 2 2.5 

Ti0 2 2.5 

Loss on ignition 25.0 

Other 1.0 

Total 100.0 

^Also contains moisture equal to 15 pet 
of the dry components. 



it is fed to an outdoor stockpile con- 
taining a 60-day supply. Equipment is 
included to transport bauxite from the 
outdoor stockpile into the storage build- 
ings when necessary. Bauxite is with- 
drawn from a storage building and sent to 
a hammer mill, where it is crushed from 
minus 6 in to minus 1 in, and then sent 
to intermediate storage bins. 

Crushed bauxite is conveyed to a rod 
mill for wet grinding to minus 20 mesh 
with a portion of the recycle caustic so- 
lution. This slurry is then pumped to 
pug mixers and mixed with lime produced 
by calcining limestone. The resulting 
slurry is pumped to storage tanks in the 
digestion section. 



BAUXITE HANDLING AND SLURRY 
PREPARATION SECTION 

Upon delivery to the plant, bauxite is 
conveyed to a hopper from where it is 
sent to one of two covered storage build- 
ings, each containing a 30-day supply, or 



DIGESTION SECTION 

Stored slurry is pumped to a line of 
four digestion vessels, which operate at 
243° C (470° F) and 525 psia. The slurry 
is mixed with the remainder of the re- 
cycle caustic solution, and steam is 



injected into the tanks to maintain the 
temperature and to agitate this slurry. 
Under these conditions , alumina in the 
bauxite forms soluble sodium aluminate in 
the following manner: 

A1 2 3 'H 2 + 2NaOH + 2NaA10 2 + 2H 2 

and A1 2 3 '3H 2 + 2NaOH 

■*■ 2NaA10 2 + 4H 2 0. 

Ninety percent of the alumina is assumed 
to react in 30 rain. 

In addition, each ton of silica in the 
bauxite combines with the dissolved alu- 
mina and caustic soda, causing losses in 
the residue equivalent to 1 ton of alu- 
mina and 1 ton of sodium carbonate. The 
reaction to which these losses are usu- 
ally attributed is 

6NaA10 2 + 5Si0 2 + 5H 2 

■* Na 6 Al 6 Si 5 22 *5H 2 0. 

A study showing the many compounds 
found in red mud has been reported in 
"Extractive Metallurgy of Aluminum" (3). 
At the same time, carbonate buildup is 
controlled and the caustic concentration 
is increased in the system by the follow- 
ing mechanism: 

Na 2 C0 3 + Ca(0H) 2 + 2NaOH + CaC0 3 . 

Exiting slurry from the digestion ves- 
sels flows to a series of nine flash 
tanks where the temperature and pressure 
are gradually reduced. Steam is recov- 
ered at the pressures shown in the mate- 
rial balance. The cooled slurry is then 
pumped to the clarification section. Re- 
covered steam is used to preheat the re- 
cycle caustic solution. The equipment 
required for preheating the solution is 
detailed in the caustic regeneration 
section. 

CLARIFICATION SECTION 

Slurry from caustic digestion is pumped 
to sand tanks, where the plus 100-mesh 



particles of red mud are removed. Over- 
flow from the sand tanks is pumped to 
thickeners , where the remainder of the 
red mud is removed. Starch is added as a 
flocculant. Depending on plant location 
and flocculant cost, flocculants other 
than starch may be used. Overflow from 
these thickeners is pumped to filter 
presses to remove any traces of solids. 
The underflow, containing 18 pet solids, 
is pumped to a series of eight wash 
thickeners , where the red mud is washed 
to recover soluble alumina and soda. 
Overflow from the wash thickeners is also 
pumped to filter presses. Filter cake, 
containing 40 pet solids , is combined 
with the underflow from the wash thicken- 
ers, reslurried, and pumped to a tailings 
pond. Green liquor from the filters is 
pumped to the precipitation and decompo- 
sition section. 

PRECIPITATION AND DECOMPOSITION SECTION 

Green liquor is pumped to 30 precipita- 
tors, 30 ft in diameter by 64-ft high. 
The supersaturated solution is seeded to 
precipitate the alumina as alumina trihy- 
drate by the following reaction: 

2NaA10 2 + 4H 2 -» A1 2 3 -3H 2 + 2NaOH. 

Seed crystals, equal to 150 pet of the 

trihydrate produced, are added to the 

precipitation tanks , and 40 h are allowed 
for precipitation. 

Alumina trihydrate slurry is pumped to 
primary thickeners , where the overflow 
containing 9 pet crystals is separated. 
Underflow from the primary thickeners is 
pumped to a fluidized-bed calciner system 
(4). There the solids are filtered, 
washed, and converted to alumina by the 
following calcination reaction, which 
occurs at 950° to 1,050° C (1,740° to 
1,920° F): 

A1 2 3 '3H 2 ■+ A1 2 3 + 3H 2 0. 

The alumina product, which contains about 
25 pet alpha-alumina, is conveyed to 
silos with a 60-day storage capacity to 
await shipment. 



Washings from the calciner filters are 
combined with the overflow from the pri- 
mary thickener and sent to secondary 
thickeners. The overflow from the sec- 
ondary thickeners , containing 1 pet sol- 
ids , flows by gravity to tertiary thick- 
eners, where the solids are separated in 
the underflow. Overflow from the terti- 
ary thickeners is pumped to the caustic 
regeneration section. Underflows from 
the secondary and tertiary thickeners are 
combined and recycled to the precipita- 
tion tanks to provide the seed crystals. 

CAUSTIC REGENERATION SECTION 



control of organic compounds and other 
minor impurities in the caustic solution. 
Water vapor is condensed and returned to 
the storage tanks along with purified 
bleed stream. 

Concentrated solution is pumped to mix- 
ing tanks, where makeup caustic is added 
to replace process losses. A portion of 
the recycle caustic solution is pumped to 
the rod mills; the remainder is preheated 
in heat exchangers, using some of the 
steam recovered from flash cooling the 
digestion liquor. The preheated recycle 
caustic is pumped to the digestion tanks. 



Clarified solution from the tertiary 
thickeners is concentrated in a six- 
effect evaporator and pumped to storage 
tanks. Water vapor is condensed and re- 
cycled to the process. A bleed stream is 
pumped from the storage tanks to a 
single-effect evaporator, where concen- 
tration allows for the removal and 



Equipment has been provided for clean- 
ing and removing scale from the heat ex- 
changers. This equipment consists of 
tanks to hold the solution that is re- 
moved from the heat exchangers , tanks 
containing a sulfuric acid cleaning solu- 
tion, tanks for the spent acid, and the 
necessary pumps and feed tanks. 



ECONOMICS 



The following cost estimate is based on 
data from literature and other nonpub- 
lished sources. 



(6) in 1980 of $800 to $1,200 per annual 
metric ton (fourth quarter 1982 equiva- 
lent $800 to $1,200 per short ton). 



CAPITAL COSTS 

The capital cost estimate is of the 
general type called a study estimate by 
Weaver and Bauman (_5) . This type of es- 
timate, prepared from a flowsheet and a 
minimum of equipment data, can be ex- 
pected to be within 30 pet of the actual 
cost for the plant described. Although 
the degree of confidence in any specific 
study estimate is not great with respect 
to the actual cost, greater confidence is 
justified when comparing a group of simi- 
lar processes evaluated by identical 
methods. The estimated fixed capital 
cost on a fourth quarter 1982 basis (Mar- 
shall and Swift (M and S) index of 749.3) 
for a plant producing 1 million tons of 
alumina per year is about $820 million as 
shown in table 2. This translates to a 
cost of about $820 per annual ton. The 
plant is designed to operate 3 shifts per 
day, 7 d/wk. This capital cost is within 
the range estimated by Hill and Robson 



Equipment costs for the process are 
based on cost-capacity data and manu- 
facturers' costs quotations. Cost data 
are brought up to date by use of infla- 
tion indexes. Capital costs for the 
fluidized-bed flash calciner are based on 
a paper by Lussky (4^) . A lined tailings 
pond for waste disposal, with a 2-yr 
life, is included in table 2. Additional 
cost will be required to construct addi- 
tional tailings pond capacity during the 
life of the plant. In developing the 
plant capital costs, corrosion-resistant 
materials of construction were used where 
appropriate. For example, the pressure- 
digestion vessels and the evaporators are 
nickel clad in order to withstand the 
high temperature and high caustic concen- 
tration of the solution. An additional 
line of equipment is included to allow 
for continuous operation of the plant 
when maintenance and scale removal are 
required for the operating equipment. 



TABLE 2. - Estimated capital cost 1 

Fixed capital: 

Bauxite handling and slurry preparation section $28,724,700 

Digestion section 87,002,000 

Clarification section 64,586,800 

Precipitation and decomposition section 107,336,100 

Caustic regeneration section 224 , 700 , 400 

Tailings pond 5,008,400 

Steamplant 27,138,500 

Subtotal 544,496,900 

Plant facilities, 10 pet of above subtotal 54,449,700 

Plant utilities, 12 pet of above subtotal 65,339,600 

Total plant cost 664,286,200 

Land cost 

Subtotal 664,286,200 

Interest during construction period 157,151,000 

Fixed capital cost 821,437,200 

Working capital: 

Raw material and supplies 8,031, 000 

Product and in-process inventory 20 , 609 , 900 

Accounts receivable 20,609, 900 

Available cash 14,882,600 

Working capital cost 64,133,400 

Capitalized startup costs 8,214,400 

Subtotal _ 72,347,800 

Total capital cost. 893,785,000 

1 Basis: M and S equipment cost index of 749.3. 



Factors for piping, etc. , except for 
the foundation and electrical factors, 
are assigned to each section, using as a 
basis the effect fluids, solids, or a 
combination of fluids and solids may have 
on the process equipment. The foundation 
cost is estimated for each piece of 
equipment individually , and a factor for 
the entire section is calculated from the 
totals. The electrical factor is based 
on motor horsepower requirements for each 
section. A factor of 10 pet, referred to 
as miscellaneous, is added to each sec- 
tion to cover minor equipment and con- 
struction costs that are not shown with 
the equipment listed. 

For each section, the field indirect 
cost, which covers field supervision, 



inspection, temporary construction, 
equipment rental, and payroll overhead, 
is estimated at 10 pet of the direct 
cost. Engineering cost is estimated at 
10 pet, and administration and overhead 
cost is estimated at 5 pet of the con- 
struction cost. A contingency allowance 
of 15 pet and a contractor's fee of 5 pet 
are included in the section cost. 

The costs of plant facilities and plant 
utilities are estimated as 10 and 12 pet, 
respectively, of the total process sec- 
tion costs and include the same field in- 
direct costs, engineering, administration 
and overhead, contingency allowance, and 
contractor's fee as are included in the 
section costs. Included under plant fa- 
cilities are the costs of material and 



labor for auxiliary buildings such as of- 
fices, shops, laboratories, and cafete- 
rias, and the cost of nonprocess equip- 
ment such as office furniture, together 
with safety, shop, and laboratory equip- 
ment. Also included are labor and mate- 
rial costs for site preparation such as 
site clearing, grading, drainage, roads, 
and fences. The cost of water, power, 
and steam distribution systems is in- 
cluded under plant utilities. 

The cost for interest on the capital 
borrowed for construction is included as 
interest during construction. Land in- 
vestment and docking facilities are not 
included in this estimate. Cost for the 
plant owner's supervision is not included 
in the capital cost of the proposed 
plant. 



oil, and coal are purchased utilities. 
The temperature of the water from the 
cooling tower is assumed to be 33° C 
(92° F) . Raw material and utility re- 
quirements per ton of alumina are shown 
in table A-l (appendix). 

The direct labor assignments are shown 
by sections in table A-2. The direct la- 
bor cost is estimated on the basis of as- 
signing 4.2 employees to each position 
that operates 24 h/d, 7 d/wk. The cost 
of labor supervision is estimated as 15 
pet of the labor cost. 

Plant maintenance is separately esti- 
mated for each piece of equipment and for 
the buildings, electrical system, piping, 
plant utility distribution systems, and 
plant facilities. 



Working capital is defined as the 
funds in addition to fixed capital, land 
investment, and startup costs that must 
be provided to operate the plant. Work- 
ing capital, also shown in table 2, is 
estimated from the following items : 
(1) Raw material and supplies inventory 
(cost of raw material and operating sup- 
plies for 30 days) , (2) product and in- 
process inventory (total operating cost 
for 30 days) , (3) accounts receivable 
(total operating cost for 30 days) , and 
(4) available cash (direct expenses for 
30 days). 

Capitalized startup costs are estimated 
as 1 pet of the fixed capital, which is 
shown in table 2. 

OPERATING COSTS 

The estimated operating costs are based 

on 365 days of operation per year over 

the life of the plant. The operating 

costs are divided into direct, indirect, 
and fixed costs. 

Direct costs include raw materials, 
utilities, direct labor, plant mainte- 
nance, payroll overhead, and operating 
supplies. The raw material costs, except 
for bauxite, do not include transporta- 
tion costs. Electricity, water, fuel 



Payroll overhead, estimated as 35 pet 
of direct labor and maintenance labor, 
includes vacation, sick leave, social 
security, and fringe benefits. The cost 
of operating supplies is estimated as 10 
pet of the cost of plant maintenance. 

Indirect costs are estimated as 25 pet 
of the direct labor and maintenance 
costs. The indirect costs include the 
expenses of control laboratories , ac- 
counting, plant protection and safety, 
plant administration, marketing, and com- 
pany overhead. Research and overall com- 
pany administrative costs outside the 
plant are not included. 

Fixed costs include the cost of taxes 
(excluding income taxes), insurance, and 
depreciation. The annual costs of both 
taxes and insurance are each estimated as 
1 pet of the plant construction cost. 
Depreciation is based on a straight-line, 
20-yr period. 

The estimated annual operating cost for 
the proposed plant is about $250 million, 
or approximately $250 per ton of alumina 
produced, as shown in table 3. This 
operating cost would be expected to vary 
from that in an existing Bayer plant be- 
cause of several factors. The design of 
an older Bayer plant generally would be 



less efficient, depreciation charges 
would be less in an older plant, and 
costs such as raw materials, transporta- 
tion, and utility rates would differ de- 
pending on plant location. In addition, 



infrastructure costs have not been con- 
sidered in this evaluation, since they 
are dependent on the individual plant 
site. 



TABLE 3. - Estimated annual operating cost 





Annual cost 


Cost 
per ton 
alumina 


Direct cost: 
Raw materials: 


$81,931,900 

471,600 

9,900,600 

1,248,300 

373,200 
476,000 


$81.92 




.47 


Starch at $180 per ton 


9.90 
1.25 


Replacement rods for grinding at $0.23 per 


.37 




.48 




94,401,600 


94.39 


Utilities: 


9,858,400 

710,400 

11,832,100 

14,504,700 


9.86 




.71 


Coal at $24.50 per ton 


11.83 




14.50 




36,905,600 


36.90 


Direct labor: 


4,542,700 
681,400 


4.54 




.68 




5,224,100 


5.22 


Plant maintenance: 


15,039,400 

3,007,900 

15,039,300 


15.04 




3.01 
15.04 


Total 


33,086,600 

8,145,000 
3,308,700 


33.09 


Operating supplies, 10 pet of plant maintenance. 


8.14 
3.31 




181,071,600 

15,324,300 

6,642,900 

6,642,900 

41,071,900 


181.05 


Indirect cost, 40 pet of direct labor and 


15.32 


Fixed cost: 


6.64 




6.64 




41.07 




250,753,600 


250.72 



REFERENCES 



1. Peters, F. A., P. W. Johnson, and 
R. C. Kirby. A Cost Estimate of the Bay- 
er Process for Producing Alumina. Bu- 
Mines RI 6730, 1966, 23 pp. 

2. Bayer, K. J. Process of Making 
Alumina. U.S. Pat. 515,895, Mar. 6, 
1894. 

3. Gerard, G. V., and P. T. Stroup. 
Extractive Metallurgy of Aluminum. In- 
terscience Publishers, New York, v. 1, 
1963, 355 pp. 



5. Weaver, J. B., and H. C. Bauman. 
Cost and Profitability Estimation. Sec. 
25 in Perry's Chemical Engineers' 
Handbook, ed. by R. H. Perry and C. H. 
Chilton. McGraw-Hill, 5th ed. , 1973, 
p. 46. 

6. Hill, V. G. , and R. J. Robson. The 
Classification of Bauxites From the Bayer 
Plant Standpoint. Light Metals, 1981, 
pp. 15-28. 



4. Lussky, E. W. Experience With 
Operation of the Alcoa Fluid Flash Cal- 
ciner. Light Metals, 1980, pp. 69-79. 



10 



APPENDIX.— UTILITY REQUIREMENTS, EQUIPMENT COST SUMMARIES, 

AND MATERIAL BALANCES 



Raw material and utility requirements 
per ton of alumina are shown in table 
A-l, and the direct labor requirements 
for each section are shown in table A-2. 
Major items of equipment for each section 
are shown in table A-3. The equipment 
costs for each section of the process are 
contained in tables A-4 to A-8. Material 

TABLE A-l. - Raw material and utility 
requirements 

Quantity 
per ton 
alumina 

Raw materials: 

Bauxite ton. . 2.643 

Limestone ton. . .118 

Sodium hydroxide, 

50-pct ton. . .057 

Starch ton. . .007 

Replacement rods for 

grinding lb . . 1.622 



balances are shown for each section in 
figures A-l to A-5. 

TABLE A-2. - Direct labor requirements, 
operators per shift 



Section 



Bauxite handling and slurry 
preparation section 

Digestion section 

Clarification section 

Precipitation and decompo- 
sition section 

Caustic regeneration 
section 

Steamplant 

General plant 

Total 



Shifts per 
week 



121 



5 
11 





36 



27 



*3 shifts per day, 7 d/wk. 
2 1 shift per day, 7 d/wk. 
3 1 shift per day, 5 d/wk. 



TABLE A-3. - Major items of equipment 



3 5 



Section and item 

Bauxite handling and slurry preparation section: 

Hammer mill , 

Rod mills , 

Pug mixers , 

Digestion section: 

Digestion tanks , 

Clarification section: 

Thickeners , 

Wash thickeners , 

Filter presses , 

Precipitation and decomposition section: 

Precipitation tanks , 

Primary thickeners , 

Fluid-flash calciners , 

Secondary thickeners , 

Tertiary thickeners , 

Caustic regeneration section: 

Multief f ect evaporators , 

Evaporator , 



Unit size 



72 by 70 in. 
7,965 ton/d. 
85 ton/h. 



12-ft diam by 37 ft, 



100-ft diam. 
100-ft diam. 
2,500 ft 2 . 



30-ft diam by 64 ft, 
25-ft diam. 
2.9 billion Btu/d. 
55-ft diam. 
110-ft diam. 



21,105 ft 2 /effect. 
23,833 ft 2 /effect. 



11 



TABLE A-4.-£qui pment cost summary* 
bauxite handling and slurry preparation section 



Item 



Equi pment 



CostCl) 



Labor 



Total 



Belt conveyor ........ • 

hopper......... 

Apron feeders*. • •• 

belt conveyors............. 

Belt conveyor.............. 

Apron feeders 

belt conveyors ••••••• 

Belt conveyors........ 

Reclaimer feeders.......... 

Belt conveyor ............. • 

Belt conveyor 

rtopper. .................... 

Apron feeder • 

Hamper mi 1 i ............... • 

Belt conveyor.............. 

Storage bins... 

Belt feeders 

Belt conveyors 

Koo mills.... 

Bridge crane 

Pumps 

Belt feeders... 

Belt conveyor...... 

Belt f eeoer ............... . 

belt conveyor. 

Hopper 

Belt feeder • 

Lime ki 1 n. ................ . 

Rotary cooler 

bag dust collectors 

celt conveyor.. • 

Surge tanks.... 

Pumps • • 

Pug mixers 

Pumps., 

Bag dust collector 

Bag dust collector 

bag dust collector......... 

Bag dust collector... 

Total 

Hoppers 

Limestone unloading hoppers 
Limestone storage silo..... 

Lime storage silo. 

Lime slakers.... 

Front-ena loaders ••••• 

Dump trucxs 

rront-end loaders 



3b 

1 

6 

32 

36 

a 

8 

69 

10 

2 

6 

1 
3 

28 
14 

9a 

4 

13 

73 

5 

a 
l 
7 



29 

10 

8 

5 

31 

2 

343 

14 

2 



9400, 
6600, 
2400. 
0000. 
1600. 
1600. 
8600, 
6300. 
3100. 
1000. 

oeoo. 

5400, 
9100. 
2400. 
7600. 
0400. 
0400. 
9900, 
6000, 
4200. 
9200, 
5500. 
6300. 
5200. 
7300. 
600. 
5200. 
7000. 
0200. 
7800, 
4400, 
6400. 
9600. 
0000. 
6S00. 
4400. 
6200. 
2200. 
620 0. 



9227400. 



82800. 

4000. 

9400. 

73800. 

81700. 

6200. 

11100. 

45800. 

15500. 

4200. 

12900. 

3500. 

5900. 

39500. 

23600. 

186600. 

6100. 

31200. 

44200. 

1700. 

9200. 

2300. 

14400. 

800. 

6300. 

100. 

800. 

89100. 

16000. 

800. 

9600. 

66400. 

7500. 

128300. 

26200. 

300. 

200. 

300. 

200. 



442200. 

20600. 

71800, 
393800. 
443300. 

47800. 

99700. 
742100, 
118600. 

25200. 

73700. 

18900. 

45000. 

321900, 

171200. 

1127000. 

46500. 
171100. 
780200, 

55900, 

58400, 

17600. 

90700. 
6000. 

33600. 

700. 

6000. 

386100. 

116200. 

88600. 

64200. 
382800. 

37100. 

3558300. 

173100. 

24700. 
6400. 

22500. 
6400. 



1068700 



(2) 
(2) 
(2) 
(2) 
U) 



10296100. 

35700. 

53600. 
382000. 
188400. 
131800. 
300800, 
204200. 

62000. 



12 



TAbLE A-4 .-Equi pment cost summary* 
oauxite handling and slurry Preparation section 

(cont i nued) 



Total equipment cost x factor indicated: 

Foundations* x .185 

Buildings* x .255... 

Structures* x .050 

Instrumentation* x .050.......... 

Electrical* x .055... 

Piping* x .050....... 

Painting* x .030 

Miscellaneous* x .100. 

Total 



Total di rect cost 



Field indirect* 10.0 pet of total direct cost 
Total construction cost 



Engineering* 10.0 pet of total construction cost 
Administration and overhead* 5.0 pot of total 

construction cost... 

Suototal..... 



Contingency* 15.0 pet of above subtotal 
Subtotal 



Contractor's fee* 5.0 pet of above subtotal 
Section cost... 



1707300. 
2354700. 

461400. 

461400. 

504900. 

461400. 

276500. 

922700. 



7150600. 



18805200. 
1880500. 



20685700. 
2068600. 
1034300. 



23788600. 
3568300. 



27356900. 
1367800. 



28724700. 



(1) Equipment costs are based on the to and S index of 749.3. 

(2) Instal 1 ed cost . 



13 



TABLE A-5,-Eoui pment cost summary/ digestion secticr 



I tern 



Equipment 



costcn 



Labor 



Total 



Slurry storage tanks 

Slurry pumps 

Digestion tanks 

F 1 ash tanks 1 • 

tanks 

tanks 

tanks 

tanks 

tanks 

tanks 

tanks 

tanks 



Flash 
Plash 
Flash 
Flash 
Flash 
Flash 
Flash 
Flash 
Pumps 



2 

3 

a 

5 
6 
7 
8 
<?, 



Total 



$ 1259200. 

1943400. 

19179700. 

343900. 

249100. 

166600. 

141000. 

141000. 

125200. 

125200. 

125200. 

125200. 

820QU. 



261900. 

74800. 
421600. 

38400. 

24500. 

17000. 

14900. 

14900. 

12500. 

12500. 

12500. 

12500. 

166QQ. 



24008700. 



934600. 



Total equipment cost x factor inoicateo: 

Foundations^ x .039........... 

duiloingsr x .004 

Structures? x .100.. 

Insulation? x .080. 

Instrumentation? x .180..... 

Electrical? x .050. 

Piping? x .700 

Painting? x .080 

Miscellaneous? x .100.. 

Total 



Total direct cost 



Fiela indirect? 10.0 pet of total direct cost 
Total construction cost 



Engineering? 10.0 pet of total construction cost 
Administration and overhead? 5.0 pet of total 

construction cost , 

Subtotal 



Contingency? 15.0 pet of above subtotal 
Subtotal 



Contractor's fee? 5.0 pet of above subtotal 
Section cost. 



1521100. 

2018200. 

19601300. 

382300. 

273600. 

185600. 

155900, 

155900. 

137700. 

137700. 

137700. 

137700. 
98600. 



24943300. 



942200 
103000 
2400900 
1920700 
4321600 
1198100 
16806100 
1920700 
2400900 



32014200 



56957500, 
5695600. 



62653300. 
6265300. 
3132700. 



72051300. 
10807700. 



82859000. 
4143000. 



87002000. 



(1) Equipment costs are based on the fo end S index of 749.3. 



14 



T A b L E A-6. -Equipment cost summary* clarification section 



Item 



Equi pment 



Cost (1) 



Labor 



Tota 



Pneumatic conveyor 

Belt feeder , 

Belt conveyor , 

Starch storage bin , 

belt feeders. 

Slurry t amcs. .......... , 

Pumps , 

Feed tanks.. < 

Pumps. ..< 

Sand tanks. ............ , 

Pumps....... ( 

Pumps.. 

Thickeners........ . 

Pumps 

Pumps .................. . 

flash thickeners , 

Pumps 

Pumps .................. , 

Filter presses.. , 

Belt conveyors... , 

Keslurry tanks 

Pumps.. ...... .......... 

Pumps... ....... ........ 

Total 

Starch unloading hopper 
Starch storage silo.... 



18100, 
5200, 
37700 
3500 
10300, 
24900, 
9900, 
31400, 
39500, 
12800, 
80200, 
20100 
2650500, 
86100, 
116100, 
10601900 
75200 
40100 
4063900 
76800 
3^300 
50900 
96200 



2000. 
600. 

9200. 

1500. 

1500. 

8300. 

1200. 

4100. 

2800. 

9500. 
12400. 

4100. 
302900. 
18000. 
24800. 
1211700. 
14900. 
11200. 
49700. 
19500. 

8900. 

8400. 
13700. 



20100. 

6000. 

46900. 

5000. 

11800. 

33200. 

11100. 

35500. 

42300. 

22300. 

92600. 

24200. 

2953400. 

104100. 

140900. 

11813600. 

90100. 

51300. 

4133600. 

96300. 

43200. 

59300. 

109900. 



16205600 



1741100. 



19946700. 
(2) 17900. 
(2) 79600. 



Total equipment cost x factor indicated; 

Foundations* x .262, • 

buildings* x .011 

Structures* x .050 

Instrumentation* x .100... 

Electrical* x .026..... 

Piping* x .600 

Painting* x .070 

Miscellaneous* x .100 

Total 



4777100. 

196900. 

910300. 
1820600. 

515500. 

10923400. 

1274400. 

1820600. 



22238800. 



Total oi rect cost 



Field indirect* 10.0 pet of total direct cost 
Total construction cost 



42283000. 
4228300. 



Engineering* 10.0 pet of total construction cost 
Administration and overhead* 5.0 pet of total 

construction cost 

Subtotal 



46511300. 
4651100. 
2325600. 



Contingency* 15.0 pet of above subtotal 
Subtotal 



53488000. 
8023200. 



Contractor's fee* 5.0 pet of above subtotal 
Section cost.. 



61511200. 



3075600. 



64586800. 



(1) Equipment costs are baseo on the M and S index of 749.3. 

(2) Insta 1 1 ed cost . 



15 



TABLE A-7. -Equipment coat summary* 
precipitation and decomposition section 



Item 



Equi pment 



Cost(l) 



Labor 



Total 



Precipitation tanks.. 

Air compressors 

Pumps. ............... 

Primary thickeners... 

Sumps 

Pumps • • 

Belt conveyors. ..... . 

Screw feeders 

Secondary thickeners. 

Sumps 

Pumps • 

Tertiary thickeners.. 

Sumps.. 

Pumps................ 

Surge tanks 

Pumps.. ••••••• 

Sumps •••• 

Pumps ...... 

Surge tanks. ........ • 

Total 

Fluid-flash calciners 
Alumina storage silos 



$10497200 

893400 

950000 

952700 

2500 

116300 

552200 

78600 

1824500 

3300 

124900 

3230200 

1200 

80400 

40700 

149300 

9200 

152800 

L0MM 



19763800 



2080100. 

10000. 

188000. 

140300. 

5400. 

21200. 

110200. 

11800. 

273700. 

6500. 

24200. 

492600. 

2900. 

13500. 

35500. 

25300. 

12300. 

38700. 

63600. 



12577300. 

903400. 

1138000. 

1093000. 

7900. 

137500. 

662400. 

90400, 

2098200. 

9800. 

149100. 

3722800. 

4100. 

93900. 

76200. 

174600. 

21500, 

191500. 

168 Q90. 



3555800. 



23319600. 
(2)18445900. 
(2) 6051500. 



Total equipment cost x factor indicated: 
Foundations, x • 32 1 .................. . 

Buildings/ x .002 

Structures* x . 050 

Instrumentation/ x .150............... 

Electrical/ x ,062., 

Piping/ x .400 

Painting/ x .050... 

Miscellaneous/ x .100 

Total 



6352600 
47600 

988200 
2964600 
1229600 
7905500 

988200 
1976400 



22452700 



Total oi rect cost 



Field indirect/ 10.0 pet of total direct cost 
Total construction cost •• 



70269700. 
7027000. 



Engineering/ 10.0 pet of total construction cost 
Administration and overhead/ 5.0 pet of total 

construction cost 

Subtotal 



77296700. 
7729700. 
3864800. 



Contingency/ 15.0 pet of above subtotal 
Suototal.. , 



88891200. 
13333700. 



Contractor's fee/ 5.0 pet of above subtotal 
Section cost •••• 



102224900. 



5111200. 



107336100. 



(1) Equipment costs are based on the V and S index of 749,3. 

(2) Instal 1 ed cost • 



16 



TABLE A-8.-Equi pment cost summary* caustic regeneration section 



Item 



fcqui pment 



CostCl) 



Labor 



Total 



Heat excnanoers 

Solution storage tanks..,. 
Acid storage tanks. ...... . 

Pumps....... ••••••• 

Feea tanks.. 

Pumps... • ••••. 

Spent acia storage tanks,. 

Pumps 

Pumps 

Mult i effect evaporators... 

Pumps 

Concentrated caustic tantcs 

Pumps.... • 

Surge tank.,,.. 

Pumps ........ • 

Evaporator 

Condensate tank..... 

Pumps.,..,., ,,, 

Pumps..................... 

Makeup storage tanks.,.,,. 
Pumps..................... 

Caustic dilution tanks,,,. 

Pumps,,,, , . . . 

Purrips......... ............ 

Pumps....... ••••• 

heat exchangers........... 

Heat exchangers........... 

Heat exchangers........... 

Heat exchangers 

heat exchangers...... 

Heat exchangers........... 

heat exchangers 

Pumps ••• 

Acid storage tanks., , 

Pumps. • •••••< 

Feea tanks , 

Pumps. 

Spent acid storage tanks,., 

Pumps., ,, 

Pumps,,,.,,, , 

Car puller,, 

Total , 

Caustic storage tanks,.... 
Solution storage tanks.,.. 
Cooling tower 



2029100 
82200 
12100 
14800 
1700 
15300 
12100 
14800 
221S00 

i909aeoo 

56500 

118300 

8000 

3700 

8800 

1564100 

1300 

7000 

5100 

464400 

79000 

2300 

59200 

68200 

94S00 

1274000 

2475300 

1683900 

1064000 

1693900 

2611600 

1609200 

736400 

35700 

20000 

2500 

21900 

35700 

19700 

502000 

3500 



57852900 



28500. 
30100. 

8800. 

3900. 

2600. 

3900. 

8600. 

3900. 

43900. 

2721900. 

12400. 

47100. 

2300. 

2800. 

2300, 
235700, 

1500. 

2000. 

1500. 
194400. 

7900. 

4000. 

7400. 
15200. 
26500. 
42100. 
65900. 
50800. 
37200. 
39700. 
53200. 
34700. 
221000. 
23500. 

5500. 

3800. 

5500. 
23500, 

5500. 

64500. 

300- 



2057600. 

112300. 

20900. 

18700. 

4300. 

19200. 

20900. 

18700, 

265800, 

41816700. 

70900. 

165400, 

10300. 

6500, 

11100. 

1799800. 

2800. 

9000. 

6600. 

678800. 

86900. 

6300. 

66600, 

83400. 

121400. 

1316100. 

2541200. 

1734700. 

1101200. 

1733600. 

2664600. 

1643900. 

959400. 

59200. 

25500. 

6300. 

27400. 

59200. 

25200. 

566500. 

3800. 



4096000. 



61948900. 
(2) 5701600. 
(2) 266900. 
(2) 885600. 



17 



TABLE A-8. -Equipment cost summary/ caustic regeneration section 

(cont inued) 



Total equipment cost x factor indicated: 

Foundations^ x .159........ 

Buildings/ x .025 

Structures/ x .050........ 

Insulation/ x .045.. •• 

Instrumentation/ x .150. 

Electrical/ x .025 

Piping/ x .750 

Painting/ x .050 

Miscellaneous, x .100.... 

Total 



Total direct cost 



Field indirect/ 10.0 pet of total direct cost 
Total construction cost...... ••••* 



Engineering/ 10.0 pet of total construction cost 
Administration and overhead/ 5.0 pet of total 

construction cost • • 

Subtotal 



Contingency/ 15.0 pet of above subtotal 
Subtotal 



Contractor's fee/ 5,0 pet of above subtotal 
Section cost ••••• 



9174500 
1464100 
2892600 
2580900 
8677900 
1443900 
43389700 
2892600 
5785300 



78301500 



147104500. 
14710500. 



161815000. 

16181500. 

8090800. 



186087300. 
27913100. 



214000400. 
10700000. 



224700400. 



(1) Equipment costs are based on the M and S index of 749.3. 

(2) Instal 1 ed cost. 



18 







Recycle caustic to 
size reduction 






AI2O3 597 
Na 2 1,351 

co 2 219 

H 2 6,743 
Total 8,910 
















Bauxi te 






A1 2 3 
Fe 2 3 
Si0 2 
LOI 
Other 
H 2 
Total 


3,088 

1,260 
156 

1,573 
219 
9^5 

7,241 




u 






SIZE REDUCTION 

















Lime 






CaO 181 




Caustic slurry 


v 




A1 2 3 3,685 
Fe 2 3 1,260 
Si0 2 156 
CaO 181 
Na 2 1,351 

co 2 219 

LOI 1,573 

Other 219 

H 2 7,688 

Total 16,332 


PUG MIXING 













FIGURE A-l. - Material balance, bauxite handling and slurry preparation section (tons per day). 



Caustic s 


urry 


AI2O3 


3,685 


Fe 2 3 


1,260 


Si0 2 


156 


CaO 
Na 2 


181 
1,351 


C0 2 


219 


LOI 


1,573 


Other 


219 


H 2 


7,688 


Total 


16,332 



Steam 



H 2 



J, 815 



DIGESTION 







Recycle caustic 
to digestion 


A1 2 3 2,225 
Na 2 5,041 

co 2 819 

H 2 25,181 
Total 33,266 



Recovered 


steam 


375 psig 


726 


250 psig 


2,035 


175 psig 


1,458 


100 psig 


1,803 


50 psig 


1,817 


30 psig 


1 ,000 


15 psig 


921 


5 psig 


885 


psig 


595 


Total 


11 ,240 



FLASH COOLING 



Digest ion 


iquor 


A1 2 3 


5,910 


Fe 2 3 


1,260 


Si0 2 


156 


CaO 


181 


Na 2 


6,392 


C0 2 


1,038 


Other 


219 


H 2 


32,017 


Total 


47,173 



FIGURE A-2. - Material balance, digestion section (tons per day). 



D igest ion 1 iquor 



A1 2 3 
Fe 2 3 
Si0 2 
CaO 
Na 2 
C0 2 
Other 
H 2 
Total 



5,910 

1,260 

156 

181 

6,392 

1,038 

219 

32,017 

47,173 



Flocculant 



Starch 



H 2 



THICKENING 



I 



WASHING 



Wash water 



11 



2*1,961 



FILTRATION 





V 




Red mud 


A1 2 3 




321 


Fe 2 3 




1,260 


Si0 2 




156 


CaO 




181 


Na 2 




115 


C0 2 




145 


Other 




219 


Starch 




19 


H 2 




10,075 


Total 




12,491 



19 



Green 


i quor 


A1 2 3 


5,589 


Na 2 


6,277 


C0 2 


893 


H 2 


46,903 


Total 


59,662 



FIGURE A-3. - Material balance, clarification section (tons per day). 



Green 


liquor 


AI2O3 
Na 2 
C0 2 
H 2 
Total 


5,589 

6,277 

893 

46,903 

59.662 






1 


1 


PRECIPITATION 



Carbon dioxide 



C0 2 



145 



Seed crystals 



A1 2 3 -3H 2 
AI2O3 
Na 2 
C0 2 
H 2 
Total 



6,264 
416 
921 
153 

6,806 



14,560 



PRIMARY THICKENING 



TERTIARY THICKENING 



Spent liquor 



A1 2 3 
Na 2 
C0 2 
H 2 
Total 



2,822 
6,272 
1,038 

4 6,355 
567487 



Wash water 



H 2 



1,485 



Stack 


gases 






A1 2 3 
H 2 
Total 




2 
2 


27 
033 
060 



FILTRATION 
AND WASHING 



SECONDARY THICKENING * 

















Alumina 


CALCINATION 


A1 2 3 
Na 2 
Total 


2,740 

5 

2,745 









'Carbon dioxide shown entering here is assumed to have 
dissolved in the system and converted some sodium 
hydroxide to sodium carbonate. 



FIGURE A-4. - Material balance, precipitation and decomposition section (tons per day), 



20 



Water vapor 



H 2 1*1,628 

T 



Makeup caustic 



Na 2 
H 2 
Total 



120 
197 
317 










Recycle caustic 
to digestion 








A1 2 3 2,225 
Na 2 5.0A) 
C0 2 819 
H 2 25,181 


EVAPORATION 


v 




m* 








Total 33,266 












Recycle caustic 
to size reduction 




A1 2 3 597 
Na 2 1,351 
C0 2 219 
H 2 6,7'»3 








Total 8,910 



FIGURE A-5. - Material balance, caustic regeneration section (tons per day). 



INT.-BU.OF MINES, PGH., PA. 27228 



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